Builders' Forum Archives

Re: I'm Watching Epoxy

It may be that the solvent wipe down is part of your problem. The amines are water soluable and thats what I use. Plain old hot water and a 3M scrubber pad. Prior to sanding.

There is lots of complex chemistry involved in epoxy. System 3 specifically cautions agains solvent washing (and even tack rags) since bonding problems can later occur. I do not believe that solvents remove the amines, they just spread it around.

I had several experiences using rubbing alcohol and a rag to wipe down a boat parts (rudder etc) to remove sanding dust from epoxy. The paint took forever to dry (days). I have not used any solvent on epoxy since and not had any paint issues - even with the same gallon of paint (see below).

I wonder if some of the chemists out there can commment on this idea??

Sam Devlin (stitch and glue boat guru) says in his book "Devlins Boatbuilding" (page 150): I would avoid the alkyd enamels...it often appears that there are chemicals in the alkyd paints that react badly with the epoxy systems....The most common complaint is that the alkyd enamels applied over epoxy take longer than normal to cure - or will not cure at all."

For what is worth, I like both Interlux Brightsides and Glidden Oil Based Poly Enhanced Porch and Floor Enamel (a modified alkyd). Both have worked for me. The paint I had a drying issue with after the alcohol wipe was Valspar Oil Based Porch Paint - poly enhanced. I still have some of that gallon and use it every year to touch up my rudder and daggerboard.